twido plc compare problem

[Riaan_bloem]

Hi all you clever people.

I have a program line that does not make sense

%MW401 < %MW402------> (%M2) - [%M2 = ON] Which does not make sense
(20 / 10)

Which will mean if 401 is smaller than 402, %m2 must switch on.
as per example above it should be off. yet it stays on.

I have a line at the end of the program that works 100%
%MW401 < %MW402 -----> (%M245) - [%M245 = OFF] Which is correct
(20 / 10)

I have searched the program and there is not a duplicate %m2.

any ideas?

tx

 

[tragically1969]

Hi all you clever people.

I have a program line that does not make sense

%MW401 < %MW402------> (%M2) - [%M2 = ON] Which does not make sense
(20 / 10)

Which will mean if 401 is smaller than 402, %m2 must switch on.
as per example above it should be off. yet it stays on.

I have a line at the end of the program that works 100%
%MW401 < %MW402 -----> (%M245) - [%M245 = OFF] Which is correct
(20 / 10)

I have searched the program and there is not a duplicate %m2.

any ideas?

tx

I don't use Twido but have you checked to see if %M2 is a system bit ? Failing that is it forced on ?

 

[nehpets]

Is %M2 actioned within a subroutine? Also if so, is that subroutine call condtioned. It could be that the subroutine call becomes false (and no longer actioned) while the status of %M2 is on, leaving it in it's last state.

Steve

 

[Lare]

is mw401 or mw402 writed multiple times on program. Maybe compare is true on network, but after that mw401 or mw402 is writed to different value.
Animation table shows values end of PLC scan

 

[Riaan_bloem]

Tx for the response so far.

The %M2 is a internal relay.
I am starting to think the problem could be the fact I am using the
%mw401 (which is a internal register as well) more that once. IE
%MW401 < %MW402 ---> %M2
and
%MW401 < %MW403 ----> %M3

But that should be the same as using the same input point more that once.

 

[chud]

It should matter how many time you are using %mw401 in a read function, like a compare block. What Lare suggested could be the fault. Do you write to %mw401 or %mw402 multiple times?

Put the %M2 in an animation table and force it off. Then unforce it to see if it comes on immediately again.

 

[Riaan_bloem]

Thanx I will try and test it again. bottom Line, I dont use %M2 as a coil more that once.
What I found strange is once I moved the line to the end of the program it worked correctly.
Contacting the Schneider office this week to see if they can spit the problem.

 

[tedfy]

interesting thread, I too was having the same problem

 

[Riaan_bloem]

Did you find any solutions?

 

[chud]

Hi Riaan
PM me the program. Your last post would indeed indicate that you are doing what Lare said and writing to %mw401 or %mw402 in different places in the program

 

[Lare]

If you put TON timer between compare and coil on original program, is coil setted still even that compare isn't true.
If coil stays now off, then problem is on scanning of program (double coil or your program writes different values to mw401, 402)